Stephen Hawking dies 55 years after being given 2 years to live

Stephen Hawking, an award-winning physicist and influential author, died early Wednesday morning, a family spokesman told ABC News. He was 76.

Hawking, whose books included "A Brief History of Time" and "The Universe in a Nutshell," was diagnosed in 1963 with Amyotrophic Lateral Sclerosis, more commonly called ALS or Lou Gehrig's disease.

The family did not disclose the cause of death, but said he "died peacefully" at his home in Cambridge, England.

"We are deeply saddened that our beloved father passed away today. He was a great scientist and an extraordinary man whose work and legacy will live on for many years," the family said in a statement. "His courage and persistence with his brilliance and humor inspired people across the world. He once said, 'It would not be much of a universe if it wasn't home to the people you love.' We will miss him forever."

Hawking leaves behind his daughter, Lucy, and two sons, Robert and Tim. They thanked his fans who have "been by Professor Hawking's side -- and supported him -- throughout his life."

Hawking was considered one of the leading voices in science because of his extensive research and work related to understanding the universe.

"I never expected to reach 75, so I feel very fortunate to be able to reflect on my legacy," Hawking said in a BBC interview last year.

He made several major discoveries throughout his career, and once said said his greatest achievement was his discovery that black holes are not entirely black.

"I think my greatest achievement will be my discovery that black holes are not entirely black," he said, adding how that discovery would be critical to "understanding how paradoxes between quantum mechanics and general relativity can be resolved."

In a 2010 interview with ABC's "World New Tonight," Hawking was asked about the best fatherly advice he'd given.

"Here are the most important pieces of advice that I've passed on to my children," he said. "One, remember to look up at the stars and not down at your feet. Two, never give up work. Work gives you meaning and purpose and life is empty without it. Three, if you are lucky enough to find love, remember it is rare and don't throw it away."

Jan. 8, 1942 - Born in Oxford, England, the eldest of four children born to Frank Hawking, a biologist, and Isobel Hawking, a medical research secretary.

1952 - Attends St. Albans School.

1959 - Receives scholarship to attend University College, Oxford, from which he graduates with a degree in Natural Science.

1962 - Begins graduate research in cosmology at Cambridge University.

1963 - Diagnosed with the degenerative nerve disorder ALS, or Lou Gehrig's disease, at the age of 21. He is given two years to live.

Jul. 14, 1965 - Marries his first wife, Jane Wilde, a modern languages student he met at Cambridge.

1967 - The couple's first son, Robert, is born.

1970 - Jane gives birth to a daughter, Lucy.

1974 - Elected as a fellow of the Royal Society at age 32, one of the youngest people to receive the honor.

1979 - Becomes Lucasian Professor of Mathematics at Cambridge, a prestigious position once held by Isaac Newton. Hawking holds the post until 2009. Jane gives birth to a third child, Timothy.

1985 - Admitted to a hospital in Geneva with pneumonia. He survives after an operation, but loses what remained of his speech. The next year he begins communicating through the electronic voice synthesizer that gave him his trademark robotic "voice."

1988 - Publishes "A Brief History of Time," a book on cosmology aimed at the general public that becomes an instant best-seller.